The IEEE 802.11 standards are used to formulate wireless local area networks (WLAN) within a radio frequency (RF) band. The radio spectrum is regulated by a regulatory authority in each country. In the United States, the Federal Communications Commission (FCC) regulates the radio spectrum. The FCC has regulated the Industrial, Scientific, and Medical (ISM) band and the Unlicensed National Information Infrastructure (U-NII) bands (e.g., U-NII-1, U-NII-2A, U-NII-2C, U-NII-3) for WLAN and mobile communications. The FCC regulates the available channels within a RF band and the key requirements for transmissions. The IEEE 802.11 standards specify a communication protocol that attempts to achieve the maximum data rate within the available channels.
Over the years, the IEEE 802.11 standards have evolved with each new standard aimed at increasing the transmission data rate by offering additional features, such as faster increased channel widths and multiple spatial streams. In some standards, such as the IEEE 802.11ac standard, an additional channel was added to the radio band thereby offering additional 20 MHz, 40 MHz, 80 MHz and 160 MHz channels. However, the advantages offered by each new standard may not be available to legacy devices still operational within a wireless network.